Many athletic endeavors require focus on a moving object (usually a ball) and subsequent coordination of bodily movement either in response to movements of the object or in an attempt to manipulate the object. In baseball for instance, a batter must focus on a ball traveling towards them while coordinating the movements required for their swing. It is believed that improving the athlete's ability to track the object of their respective sport will improve athletic performance.
Gaze defines a subject's current line of sight or fixation point. The fixation point is defined as the intersection of the line of sight with the surface of the object being viewed. In recent years significant research has been devoted to studying gaze and eye position relative to performance in activities that require hand-eye coordination. Much of the research has focused on the use of gaze tracking in athletic training.
One area of research currently being conducted is the relationship of eye gaze time, targeting and performance levels. On-going research on targeting in sports is revealing intriguing secrets of how elite athletes utilize their eyes to target in a number of sports including baseball, golf, hockey and tennis. Specifically, this research informs us where to best target with our eyes and how long to actually fix our gaze on our target. And, the research is providing insight in targeting proficiency that will allow more novice players to alter their targeting to improve performance.
Research has shown that athletes that perform at a high level are better able to coordinate eye gaze and head movement, or rather coordinate them in a different (or more optimal) manner than their less-accomplished counterparts. It is believed, with an effective system for tracking the two movements (gaze and head movement) coupled with correlating the movements to the actual position of a moving object (e.g., a tennis ball), that performance in sports such as baseball and tennis can be improved by training athletes to coordinate these movements in an optimal fashion.
Existing techniques for eye gaze tracking can be divided into video-based techniques and non-video-based techniques. The non-video-based methods typically use special contacting devices attached to the skin or eye to obtain the subject's gaze. Thus, the non-video-based methods are intrusive and interfere with the subject. In contrast, video-based gaze tracking methods have the advantage of being unobtrusive and comfortable for the subject during the process of gaze estimation. Unfortunately, current video-based gaze tracking methods have significant shortcomings. For example, some existing techniques which relate gaze to head orientation lack sufficient accuracy. Other existing techniques which relate gaze to eye orientation require a static head which is a significant constraint imposed on the subject. Another serious problem with the existing eye and gaze tracking systems is the need to perform a rather cumbersome calibration process for each individual.
If one is to develop a system to evaluate head movement and gaze tracking in the realm of athletic training, the ability to track and analyze these data simultaneously, as well as while the subject is performing the required task, is needed. Thus, a system that is not overly cumbersome, and allows freedom of motion while monitoring and recording the necessary movements, is needed.
In recent years, research has indicated that elite athletes in sports that require focus on an object that is rapidly approaching the athlete (such as tennis and baseball) coordinate both their head and eye movements in a similar and predictable fashion, and that less accomplished athletes in these sports tend to utilize a different combination of head movement and eye gaze coordination. Researchers then deduced that training in the realm of gaze tracking could improve athletic performance.
The field of gaze tracking has been studied for many years, mainly in an effort to improve human-computer interface. Much of the technology has developed around so-called glint tracking. Glint refers to the reflection off of the surface of the eye of directed light. The shape of the light source creates a recognizable pattern on the surface of the eye which can be tracked and, using simple concepts from the field of optics, can be used to determine the direction of the subject's gaze and their point of regard. Glint tracking in its most basic form involves a light focused on the subject's eye, a video recording device to monitor the shape and position of the glint, and a software program that is able to analyze the video recording and calculate changes in the shape and position of the glint and correlate that to eye position and point of regard.
One of the first obstacles to overcome when developing a glint tracking system is that of size/portability. In order to be most effective, the light for the glint tracking and the video recording device must be positioned close to the eye or interference from other objects will become a problem. Additionally, more accurate measurements may be made while in close proximity to the eye. This obstacle is often addressed by attaching the light source and video camera to a set of goggles or some type of apparatus that fits over the crown of the head and projects over the front of the head, giving the lights and camera access to the eyes. An example of an apparatus that addresses these issues is manufactured by ISCAN Incorporated, 89 Cambridge Street Burlington, Mass. 01803.
Another obstacle is effective tracking of movements of the head. Systems of the past required a clear line of sight between the sensor and the transmitter due to the fact that they employed light or sound energy to track motion. Data transmission would be disrupted, in devices that employ light or sound energy to track motion, if a clear line of sight was not maintained. This results in suboptimal or limited adaptability to activities that require the motion of other objects or appendages of the subject (i.e., movement of the subject's hand during tracking would impede the tracking capabilities or disrupt data acquisition thus restricting the system to a limited set of applications).
One solution that those interested in tracking body motion developed, while avoiding the drawbacks of light or sound-based technologies, was to create a magnetic field about the object to be tracked. When the participant's head is turned within the generated magnetic field, a signal is induced in the receiver that is proportional to the amount of head turn. This signal may be read by a computer. One apparatus that uses this technology is manufactured by Ascension Technology Corp. P.O. Box 527 Burlington, Vt. 05402.
An additional variable in determining whether a test subject is appropriately tracking a moving object, is the position of the “pitched object,” whether a baseball, a tennis ball, or any other object that a test subject might be attempting to track. It is advantageous to reduce the amount of variability in, or at least to be able to have some control over, the position and speed of the pitched object. This can be accomplished by using a pitching machine; these are available for a number of sports including baseball, softball, tennis, and football among others. The basic idea is that the ball of the particular sport is pitched by the machine using either mechanical means or compressed gas. The fact that most of these machines have speed and angle adjustments allows the trainer to reduce the amount of variability that would otherwise be present if the pitched object was delivered by a human. An example of a machine developed for use in baseball training is available from Accelerated Baseball Tech. Inc. 28500 West Heritage Oak Road Barrington, Ill. 60010.
Another obstacle in developing a system for effective training of head movement and gaze tracking is the ability to coordinate the data from these sources. The data regarding gaze, head motion and the relative position of the projected object need to be analyzed at specific points in time in order to determine how well the participant is tracking the projected object, or to detect any errors in gaze position.
These and other unmet needs of the known art may be met by a system and method as described in more detail below. For instance, one example of the present invention is a method for improving visual tracking ability comprising the steps of: providing a machine for projecting an object generally toward a participant; projecting the object toward a participant; determining the participant's tracking ability; and providing feedback regarding the participant's tracking ability. Another exemplary embodiment of the present invention is a system for improving the visual tracking ability of a participant. An example of a system may comprise: a machine for projecting an object at the participant; a means for tracking the gaze of the participant; a means for tracking the head movement of the participant; and a means for tracking the relative position of the projected object. Yet another embodiment of a system for improving the visual tracking ability of a participant comprises: a machine adapted to project an object at the participant; at least one camera adapted to be utilized in such a way as to track the gaze of the participant; at least one camera adapted to be used to track the position of the projected object relative to the participant; an apparatus adapted to utilize an induced magnetic field to track the movement of the participant's head; and a computer system capable of receiving data from the various tracking apparatuses and, via computer readable instructions, correlating the data with respect to time. An example of a computer system may comprise: one or more processors or processing units; a system memory; a system bus that may couple or associate various system components such as the processor and the various tracking apparatuses to the system memory; and a monitor for displaying the coordinated data. Other embodiments may utilize some or all of the aforementioned features. In view of these exemplary embodiments, still other variations are possible such as described below.